It is known in the art to provide containers for storing and transporting all types of materials. Such containers are typically in the shape of drums, but any number of configurations could be used so long as a reliable and resealable opening to the interior of the container is provided for filling and emptying the contents therein. Containers that hold liquids are particularly troublesome in that openings must be reliably mounted and sealed to the container to prevent leakage therebetween during transport and especially after being subjected to some type of external force applied to the container opening.
Conventional containers of this type typically include a sheet metal wall having a bunghole or opening for emptying or filling the container. The opening is usually defined by a closure bushing having an internally-threaded neck that can received an externally-threaded plug for sealing the opening and thus the contents of the container. The container wall typically includes an upwardly extending collar which surrounds the closure bushing.
When the closure bushing is fitted within the container wall collar, the closure bushing base flange is firmly pressed against the interior of the container wall collar with a sealing member compressed or wedged therebetween to provide the required seal. A second closure bushing flange is then flanged over the collar of the container opening so that the sealing ring can be held firmly wedged with pre-tension in this position. Therefore, when the closure bushing is secured within the container wall collar, the sealing member is wedged between the two parts and deformed, and because the sealing member material, such as rubber, retains its resiliency, the sealing member will insure a permanent seal.
The required closure seal is maintained so long as the sealing member is held firmly wedged between the closure bushing and container wall collar. However, as soon as the wedging reduces, the risk of leakage occurs between the container wall collar and the closure bushing. Such a reduction of the wedging can occur if the drum falls from a certain height onto a hard surface with the closure down. The closure bushing and upwardly extending container wall collar, which project upwardly relative to the rest of the container wall, may be pressed inwardly or bent in this case and could result in the closure bushing and the container wall collar being forced apart. Further, because containers are typically made of sheet metal, any bending or deformation of the container wall or upstanding container wall collar could result in the closure bushing and the container wall or container wall collar being forced apart permanently, thereby permitting leakage of liquid therebetween.
As a result, if the container wall or container wall collar is deformed to the extent that proper wedging is reduced, the seal cannot be maintained and leakage will likely occur. Currently, the prior art has attempted to solve this problem by reinforcing the seal between the closure bushing and the container wall collar. One such reference is U.S. Pat. No. 5,853,100 issued to Kars that discloses a drum with drum closure method that attempts to prevent leaking due to the deformation or compromise of the first seal by providing a second seal between the collar and the closure bushing or insert. As a result of the position of the additional seal between the collar and the insert, the '100 patent attempts to ensure that a proper seal is maintained even if the insert is pressed inwards relative to the collar as the result of a fall.
However, because the nature and extent of damage caused by external forces is unpredictable, utilizing a second seal will not likely prevent leakage in all cases, particularly when the external force impacts the closure bushing and container wall collar at an angle. In such a case, the container wall or container wall collar may be deformed to such an extent that both seals are compromised. Therefore, there is a need in the art to provide a container and container closure assembly that will maintain its seal wedge during the application of an external force that could cause container wall or container wall collar deformation.